The gypsum scarp

A cliff along the edge of the gypsum!

A view over the gypsum karstic landscape shows that this peculiar geomorphology is often associated with strong contrasts in lithology and structure between the gypsum itself and the surrounding rocks. On a large scale, the gypsum karst landscape stands out because the gypsiferous outcrops almost always lie at a higher level than the neighbouring deposits (such as the marls and clays), forming a large platform with a scarp edge.

What is the explanation for this “inverted relief”? It is caused by the geological development of the karst itself. While gypsum tends to dissolve and form caves at depth, the marls and clays are eroded from the surface downwards. After hundreds of thousands of years a scarp face is formed by the gypsum outcrops right along the contact with the marls and clays, giving rise to the impressive contrasts in the landscape.

The process of formation of the gypsum scarp can be seen along the Río de Aguas, where large collapses of gypsum blocks are evidence of the gradual recession of the gypsum scarp over hundreds of thousands of years (Figure 6).

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